I always used the small child trapped in a tumbleweed scale myself. And for judging rainfall, the speed at which a homeless person clutching a mattress traveled down the arroyo.
When I worked at Sun Healthcare, there was one day during a monsoon storm that a co-worker and I were watching the arroyo that bisected the campus fill up, and we joked about all the detritus that comes tumbling down when the waters flow. "Shopping carts, tumbleweeds, people..."
Next thing you know, this guy goes whooshing by, and looks right at us. We were up on the third floor of the building, so we couldn't do much, but a couple of others rushed out of the first floor and tried to catch him. The ABQ fire department eventually saved the day.
This was about 10 years ago, IIRC.